The present invention relates to a processor chip for a computer and, more particularly, to a processor chip package that contains elastomeric elements for spring biasing an electronic chip to a heat sink with a controlled gap between the processor chip and the bottom surface of the heat sink.
As computer chips become more sophisticated and powerful, it is well known that the requirement to dissipate the heat generated by the chips, also increases. An obvious and conventional solution has been to associate ever larger heat sinks with such powerful chips. In general, however, the larger the heat sink, the greater its weight. Such weight, when supported by the chip itself, produces significant stress on the relatively fragile electrical connections (e.g., an array of solder balls, columns or pads) between the chip and its mother board.
Mounting a processor chip to a mother board of a computer is often accomplished by means of a latching mechanism that biasly clamps the chip into engagement with a heat sink surface. This type of mounting package is taught or illustrated, for example, in U.S. Pat. Nos. 5,572,404 and 5,307,239, issued to Layton et al, and Tustaniwskyj et al respectively. It is necessary to maintain a positive bias between the chip and the heat sink in order for good thermal contact to be maintained. The aforementioned mounting package, while efficient, is expensive to manufacture.
In recent times, there has been increased market pressure to decrease the cost of personal computers in order to maintain sales and market share. One of the ways to accomplish this objective is to simplify the design of the computer and its components, thus reducing its cost.
One of the objects of the present invention is to provide a simplified mounting package for the processor chip of a personal computer, one that isolates the fragile solder balls of the chip from forces such as shock, for example. The inventive design places the chip very close to a heat spreader plate that carries a heat sink. The card carrying the chip is preloaded against a spreader plate with a pair of elastomer disks or other mechanical springs (e.g., steel springs) that provide a constant spring bias. A thin layer of thermal grease is placed between the processor chip and the heat spreader plate. In order to provide thermal reliability, a minimum gap must be maintained between the chip and the heat absorbing surface of the spreader plate. This consistent gap is achieved by a boss/standoff that is fabricated on the undersurface of the heat spreader plate.
The card carrying the chip is aligned by four guide posts extending from the heat spreader plate. The guide posts fit into a plastic cover plate. The plastic cover assembly permanently snaps into holes provided in the heat spreader plate. The cover supports two elongated retention latches that mate with slots in the spreader plate. Several latch embodiments can be utilized with the invention. The preferred embodiment comprises latches that are molded as one long piece with an integral center spring.
The aforementioned packaging design provides a simplified, low cost design that is consistent with the objectives of this invention. The assembly of the chip package is simple and can easily be disassembled to replace or rework its components. The processor chip package is designed to interconnect with a personal computer mother board via a card slot connector, such as a Slot 1 or Slot 2 connector.
In U.S. Pat. No. 4,521,829, issued to Wessely, on Jun. 4, 1985, for DEVICE FOR COOLING A PLURALITY OF INTEGRATED MODULES COMBINED ON A RIGID PRINTED CIRCUIT BOARD TO FORM LOGIC CARDS, a plurality of integrated modules is illustrated. The modules are spring mounted to a cooling plate above a supporting circuit board.
In U.S. Pat. No. 5,572,404, issued to Layton et al, on Nov. 5, 1996, for HEAT TRANSFER MODULE INCORPORATING LIQUID METAL SQUEEZED FROM A COMPLIANT BODY, a circular spring retainer is utilized to bias an integrated circuit against a heat sink.
In U.S. Pat. No. 5,430,611, issued to Patel et al, on Jul. 4, 1995, for SPRING-BIASED HEAT SINK ASSEMBLY FOR A PLURALITY OF INTEGRATED CIRCUITS ON A SUBSTRATE, a mounting package is illustrated that biasly attaches integrated circuits to a heat sink by a plurality of beam springs.
In accordance with the present invention, there is provided an electronic package for mounting a semiconductor chip to its circuit board. The electronic package contains a circuit card which supports an electronic chip. The semiconductor chip is attached to the chip carrier plate by an array of solder bumps or balls. A heat spreader plate supporting a heat sink is spring loaded against the semiconductor chip by means of elastomeric disks disposed upon a spring retainer plate that, itself, is disposed adjacent the chip carrier plate. A plastic cover both protects and supports the heat sink and the semiconductor chip. A retention latch is disposed between the cover plate and the spring retainer plate.
The electronic package can be utilized as a mount for a processor chip that plugs into a Slot 1, Slot 2 or other such connector on a personal computer mother board.
It is an object of this invention to provide an improved, low cost, electronic package for a semiconductor chip.
It is another object of this invention to provide a low cost, electronic package for a processor chip that mounts to a mother board in a personal computer.
It is still another object of this invention to provide an electronic package for a processor chip, used in conjunction with a heat sink, that isolates the fragile electrical connections of the chip from the weight of the heat sink and from other forces such as shock, for example.
It is yet another object of this invention to reduce the constant loading of the solder joints to improve reliability.
It is still another object of the invention to reduce the tolerance effects on the assembly.